The season--January and February, 1951
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Maryland Birdlife↗
Geology topics
C.S. Robbins
Publications and source records attributed to C.S. Robbins.
Fifty-first Christmas bird count. Summary of highest counts of individuals
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Audubon Field Notes↗
Fifty-first Christmas bird count. 134. Ocean City, Md
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Audubon Field Notes↗
Ecological Distribution of the Breeding Parulidae of Maryland
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Book↗
The changing seasons: A summary of the spring migration
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Audubon Field Notes↗
Preliminary map showing the winter distribution of the king rail (Rallus elegans elegans)
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Audubon Field Notes↗
Preliminary map showing the winter distribution of the clapper rail (Rallus longirostris subsp.) in the United States
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Audubon Field Notes↗
Hawks over Maryland, fall of 1949
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Maryland Birdlife↗
Distribution of North American birds: Winter distribution of the sora
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Audubon Field Notes↗
Black vultures in western Pennsylvania
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The Wilson Bulletin↗
The season--May, June, July, and August 1950
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Maryland Birdlife↗
The season--September and October 1950
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Maryland Birdlife↗
The season--November and December, 1949
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Maryland Birdlife↗
The season--January and February 1950
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Maryland Birdlife↗
The season--March and April, 1950
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Maryland Birdlife↗
The changing seasons. A summary of the nesting season
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Audubon Field Notes↗
Snowy owls were recorded on 58 Christmas counts this year [map]
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Audubon Field Notes↗
Fiftieth Christmas bird count. A summary of largest counts of individuals
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Audubon Field Notes↗